| 1 | /* |
| 2 | * CPU subsystem support |
| 3 | */ |
| 4 | |
| 5 | #include <linux/kernel.h> |
| 6 | #include <linux/module.h> |
| 7 | #include <linux/init.h> |
| 8 | #include <linux/sched.h> |
| 9 | #include <linux/cpu.h> |
| 10 | #include <linux/topology.h> |
| 11 | #include <linux/device.h> |
| 12 | #include <linux/node.h> |
| 13 | #include <linux/gfp.h> |
| 14 | #include <linux/slab.h> |
| 15 | #include <linux/percpu.h> |
| 16 | #include <linux/acpi.h> |
| 17 | #include <linux/of.h> |
| 18 | #include <linux/cpufeature.h> |
| 19 | |
| 20 | #include "base.h" |
| 21 | |
| 22 | static DEFINE_PER_CPU(struct device *, cpu_sys_devices); |
| 23 | |
| 24 | static int cpu_subsys_match(struct device *dev, struct device_driver *drv) |
| 25 | { |
| 26 | /* ACPI style match is the only one that may succeed. */ |
| 27 | if (acpi_driver_match_device(dev, drv)) |
| 28 | return 1; |
| 29 | |
| 30 | return 0; |
| 31 | } |
| 32 | |
| 33 | #ifdef CONFIG_HOTPLUG_CPU |
| 34 | static void change_cpu_under_node(struct cpu *cpu, |
| 35 | unsigned int from_nid, unsigned int to_nid) |
| 36 | { |
| 37 | int cpuid = cpu->dev.id; |
| 38 | unregister_cpu_under_node(cpuid, from_nid); |
| 39 | register_cpu_under_node(cpuid, to_nid); |
| 40 | cpu->node_id = to_nid; |
| 41 | } |
| 42 | |
| 43 | static int __ref cpu_subsys_online(struct device *dev) |
| 44 | { |
| 45 | struct cpu *cpu = container_of(dev, struct cpu, dev); |
| 46 | int cpuid = dev->id; |
| 47 | int from_nid, to_nid; |
| 48 | int ret; |
| 49 | |
| 50 | from_nid = cpu_to_node(cpuid); |
| 51 | if (from_nid == NUMA_NO_NODE) |
| 52 | return -ENODEV; |
| 53 | |
| 54 | ret = cpu_up(cpuid); |
| 55 | /* |
| 56 | * When hot adding memory to memoryless node and enabling a cpu |
| 57 | * on the node, node number of the cpu may internally change. |
| 58 | */ |
| 59 | to_nid = cpu_to_node(cpuid); |
| 60 | if (from_nid != to_nid) |
| 61 | change_cpu_under_node(cpu, from_nid, to_nid); |
| 62 | |
| 63 | return ret; |
| 64 | } |
| 65 | |
| 66 | static int cpu_subsys_offline(struct device *dev) |
| 67 | { |
| 68 | return cpu_down(dev->id); |
| 69 | } |
| 70 | |
| 71 | void unregister_cpu(struct cpu *cpu) |
| 72 | { |
| 73 | int logical_cpu = cpu->dev.id; |
| 74 | |
| 75 | unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); |
| 76 | |
| 77 | device_unregister(&cpu->dev); |
| 78 | per_cpu(cpu_sys_devices, logical_cpu) = NULL; |
| 79 | return; |
| 80 | } |
| 81 | |
| 82 | #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE |
| 83 | static ssize_t cpu_probe_store(struct device *dev, |
| 84 | struct device_attribute *attr, |
| 85 | const char *buf, |
| 86 | size_t count) |
| 87 | { |
| 88 | ssize_t cnt; |
| 89 | int ret; |
| 90 | |
| 91 | ret = lock_device_hotplug_sysfs(); |
| 92 | if (ret) |
| 93 | return ret; |
| 94 | |
| 95 | cnt = arch_cpu_probe(buf, count); |
| 96 | |
| 97 | unlock_device_hotplug(); |
| 98 | return cnt; |
| 99 | } |
| 100 | |
| 101 | static ssize_t cpu_release_store(struct device *dev, |
| 102 | struct device_attribute *attr, |
| 103 | const char *buf, |
| 104 | size_t count) |
| 105 | { |
| 106 | ssize_t cnt; |
| 107 | int ret; |
| 108 | |
| 109 | ret = lock_device_hotplug_sysfs(); |
| 110 | if (ret) |
| 111 | return ret; |
| 112 | |
| 113 | cnt = arch_cpu_release(buf, count); |
| 114 | |
| 115 | unlock_device_hotplug(); |
| 116 | return cnt; |
| 117 | } |
| 118 | |
| 119 | static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store); |
| 120 | static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store); |
| 121 | #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */ |
| 122 | #endif /* CONFIG_HOTPLUG_CPU */ |
| 123 | |
| 124 | struct bus_type cpu_subsys = { |
| 125 | .name = "cpu", |
| 126 | .dev_name = "cpu", |
| 127 | .match = cpu_subsys_match, |
| 128 | #ifdef CONFIG_HOTPLUG_CPU |
| 129 | .online = cpu_subsys_online, |
| 130 | .offline = cpu_subsys_offline, |
| 131 | #endif |
| 132 | }; |
| 133 | EXPORT_SYMBOL_GPL(cpu_subsys); |
| 134 | |
| 135 | #ifdef CONFIG_KEXEC |
| 136 | #include <linux/kexec.h> |
| 137 | |
| 138 | static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr, |
| 139 | char *buf) |
| 140 | { |
| 141 | struct cpu *cpu = container_of(dev, struct cpu, dev); |
| 142 | ssize_t rc; |
| 143 | unsigned long long addr; |
| 144 | int cpunum; |
| 145 | |
| 146 | cpunum = cpu->dev.id; |
| 147 | |
| 148 | /* |
| 149 | * Might be reading other cpu's data based on which cpu read thread |
| 150 | * has been scheduled. But cpu data (memory) is allocated once during |
| 151 | * boot up and this data does not change there after. Hence this |
| 152 | * operation should be safe. No locking required. |
| 153 | */ |
| 154 | addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum)); |
| 155 | rc = sprintf(buf, "%Lx\n", addr); |
| 156 | return rc; |
| 157 | } |
| 158 | static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL); |
| 159 | |
| 160 | static ssize_t show_crash_notes_size(struct device *dev, |
| 161 | struct device_attribute *attr, |
| 162 | char *buf) |
| 163 | { |
| 164 | ssize_t rc; |
| 165 | |
| 166 | rc = sprintf(buf, "%zu\n", sizeof(note_buf_t)); |
| 167 | return rc; |
| 168 | } |
| 169 | static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL); |
| 170 | |
| 171 | static struct attribute *crash_note_cpu_attrs[] = { |
| 172 | &dev_attr_crash_notes.attr, |
| 173 | &dev_attr_crash_notes_size.attr, |
| 174 | NULL |
| 175 | }; |
| 176 | |
| 177 | static struct attribute_group crash_note_cpu_attr_group = { |
| 178 | .attrs = crash_note_cpu_attrs, |
| 179 | }; |
| 180 | #endif |
| 181 | |
| 182 | static const struct attribute_group *common_cpu_attr_groups[] = { |
| 183 | #ifdef CONFIG_KEXEC |
| 184 | &crash_note_cpu_attr_group, |
| 185 | #endif |
| 186 | NULL |
| 187 | }; |
| 188 | |
| 189 | static const struct attribute_group *hotplugable_cpu_attr_groups[] = { |
| 190 | #ifdef CONFIG_KEXEC |
| 191 | &crash_note_cpu_attr_group, |
| 192 | #endif |
| 193 | NULL |
| 194 | }; |
| 195 | |
| 196 | /* |
| 197 | * Print cpu online, possible, present, and system maps |
| 198 | */ |
| 199 | |
| 200 | struct cpu_attr { |
| 201 | struct device_attribute attr; |
| 202 | const struct cpumask *const * const map; |
| 203 | }; |
| 204 | |
| 205 | static ssize_t show_cpus_attr(struct device *dev, |
| 206 | struct device_attribute *attr, |
| 207 | char *buf) |
| 208 | { |
| 209 | struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr); |
| 210 | int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map)); |
| 211 | |
| 212 | buf[n++] = '\n'; |
| 213 | buf[n] = '\0'; |
| 214 | return n; |
| 215 | } |
| 216 | |
| 217 | #define _CPU_ATTR(name, map) \ |
| 218 | { __ATTR(name, 0444, show_cpus_attr, NULL), map } |
| 219 | |
| 220 | /* Keep in sync with cpu_subsys_attrs */ |
| 221 | static struct cpu_attr cpu_attrs[] = { |
| 222 | _CPU_ATTR(online, &cpu_online_mask), |
| 223 | _CPU_ATTR(possible, &cpu_possible_mask), |
| 224 | _CPU_ATTR(present, &cpu_present_mask), |
| 225 | }; |
| 226 | |
| 227 | /* |
| 228 | * Print values for NR_CPUS and offlined cpus |
| 229 | */ |
| 230 | static ssize_t print_cpus_kernel_max(struct device *dev, |
| 231 | struct device_attribute *attr, char *buf) |
| 232 | { |
| 233 | int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1); |
| 234 | return n; |
| 235 | } |
| 236 | static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); |
| 237 | |
| 238 | /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ |
| 239 | unsigned int total_cpus; |
| 240 | |
| 241 | static ssize_t print_cpus_offline(struct device *dev, |
| 242 | struct device_attribute *attr, char *buf) |
| 243 | { |
| 244 | int n = 0, len = PAGE_SIZE-2; |
| 245 | cpumask_var_t offline; |
| 246 | |
| 247 | /* display offline cpus < nr_cpu_ids */ |
| 248 | if (!alloc_cpumask_var(&offline, GFP_KERNEL)) |
| 249 | return -ENOMEM; |
| 250 | cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask); |
| 251 | n = cpulist_scnprintf(buf, len, offline); |
| 252 | free_cpumask_var(offline); |
| 253 | |
| 254 | /* display offline cpus >= nr_cpu_ids */ |
| 255 | if (total_cpus && nr_cpu_ids < total_cpus) { |
| 256 | if (n && n < len) |
| 257 | buf[n++] = ','; |
| 258 | |
| 259 | if (nr_cpu_ids == total_cpus-1) |
| 260 | n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids); |
| 261 | else |
| 262 | n += snprintf(&buf[n], len - n, "%d-%d", |
| 263 | nr_cpu_ids, total_cpus-1); |
| 264 | } |
| 265 | |
| 266 | n += snprintf(&buf[n], len - n, "\n"); |
| 267 | return n; |
| 268 | } |
| 269 | static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); |
| 270 | |
| 271 | static void cpu_device_release(struct device *dev) |
| 272 | { |
| 273 | /* |
| 274 | * This is an empty function to prevent the driver core from spitting a |
| 275 | * warning at us. Yes, I know this is directly opposite of what the |
| 276 | * documentation for the driver core and kobjects say, and the author |
| 277 | * of this code has already been publically ridiculed for doing |
| 278 | * something as foolish as this. However, at this point in time, it is |
| 279 | * the only way to handle the issue of statically allocated cpu |
| 280 | * devices. The different architectures will have their cpu device |
| 281 | * code reworked to properly handle this in the near future, so this |
| 282 | * function will then be changed to correctly free up the memory held |
| 283 | * by the cpu device. |
| 284 | * |
| 285 | * Never copy this way of doing things, or you too will be made fun of |
| 286 | * on the linux-kernel list, you have been warned. |
| 287 | */ |
| 288 | } |
| 289 | |
| 290 | #ifdef CONFIG_GENERIC_CPU_AUTOPROBE |
| 291 | static ssize_t print_cpu_modalias(struct device *dev, |
| 292 | struct device_attribute *attr, |
| 293 | char *buf) |
| 294 | { |
| 295 | ssize_t n; |
| 296 | u32 i; |
| 297 | |
| 298 | n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:", |
| 299 | CPU_FEATURE_TYPEVAL); |
| 300 | |
| 301 | for (i = 0; i < MAX_CPU_FEATURES; i++) |
| 302 | if (cpu_have_feature(i)) { |
| 303 | if (PAGE_SIZE < n + sizeof(",XXXX\n")) { |
| 304 | WARN(1, "CPU features overflow page\n"); |
| 305 | break; |
| 306 | } |
| 307 | n += sprintf(&buf[n], ",%04X", i); |
| 308 | } |
| 309 | buf[n++] = '\n'; |
| 310 | return n; |
| 311 | } |
| 312 | |
| 313 | static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env) |
| 314 | { |
| 315 | char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL); |
| 316 | if (buf) { |
| 317 | print_cpu_modalias(NULL, NULL, buf); |
| 318 | add_uevent_var(env, "MODALIAS=%s", buf); |
| 319 | kfree(buf); |
| 320 | } |
| 321 | return 0; |
| 322 | } |
| 323 | #endif |
| 324 | |
| 325 | /* |
| 326 | * register_cpu - Setup a sysfs device for a CPU. |
| 327 | * @cpu - cpu->hotpluggable field set to 1 will generate a control file in |
| 328 | * sysfs for this CPU. |
| 329 | * @num - CPU number to use when creating the device. |
| 330 | * |
| 331 | * Initialize and register the CPU device. |
| 332 | */ |
| 333 | int register_cpu(struct cpu *cpu, int num) |
| 334 | { |
| 335 | int error; |
| 336 | |
| 337 | cpu->node_id = cpu_to_node(num); |
| 338 | memset(&cpu->dev, 0x00, sizeof(struct device)); |
| 339 | cpu->dev.id = num; |
| 340 | cpu->dev.bus = &cpu_subsys; |
| 341 | cpu->dev.release = cpu_device_release; |
| 342 | cpu->dev.offline_disabled = !cpu->hotpluggable; |
| 343 | cpu->dev.offline = !cpu_online(num); |
| 344 | cpu->dev.of_node = of_get_cpu_node(num, NULL); |
| 345 | #ifdef CONFIG_GENERIC_CPU_AUTOPROBE |
| 346 | cpu->dev.bus->uevent = cpu_uevent; |
| 347 | #endif |
| 348 | cpu->dev.groups = common_cpu_attr_groups; |
| 349 | if (cpu->hotpluggable) |
| 350 | cpu->dev.groups = hotplugable_cpu_attr_groups; |
| 351 | error = device_register(&cpu->dev); |
| 352 | if (!error) |
| 353 | per_cpu(cpu_sys_devices, num) = &cpu->dev; |
| 354 | if (!error) |
| 355 | register_cpu_under_node(num, cpu_to_node(num)); |
| 356 | |
| 357 | return error; |
| 358 | } |
| 359 | |
| 360 | struct device *get_cpu_device(unsigned cpu) |
| 361 | { |
| 362 | if (cpu < nr_cpu_ids && cpu_possible(cpu)) |
| 363 | return per_cpu(cpu_sys_devices, cpu); |
| 364 | else |
| 365 | return NULL; |
| 366 | } |
| 367 | EXPORT_SYMBOL_GPL(get_cpu_device); |
| 368 | |
| 369 | #ifdef CONFIG_GENERIC_CPU_AUTOPROBE |
| 370 | static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL); |
| 371 | #endif |
| 372 | |
| 373 | static struct attribute *cpu_root_attrs[] = { |
| 374 | #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE |
| 375 | &dev_attr_probe.attr, |
| 376 | &dev_attr_release.attr, |
| 377 | #endif |
| 378 | &cpu_attrs[0].attr.attr, |
| 379 | &cpu_attrs[1].attr.attr, |
| 380 | &cpu_attrs[2].attr.attr, |
| 381 | &dev_attr_kernel_max.attr, |
| 382 | &dev_attr_offline.attr, |
| 383 | #ifdef CONFIG_GENERIC_CPU_AUTOPROBE |
| 384 | &dev_attr_modalias.attr, |
| 385 | #endif |
| 386 | NULL |
| 387 | }; |
| 388 | |
| 389 | static struct attribute_group cpu_root_attr_group = { |
| 390 | .attrs = cpu_root_attrs, |
| 391 | }; |
| 392 | |
| 393 | static const struct attribute_group *cpu_root_attr_groups[] = { |
| 394 | &cpu_root_attr_group, |
| 395 | NULL, |
| 396 | }; |
| 397 | |
| 398 | bool cpu_is_hotpluggable(unsigned cpu) |
| 399 | { |
| 400 | struct device *dev = get_cpu_device(cpu); |
| 401 | return dev && container_of(dev, struct cpu, dev)->hotpluggable; |
| 402 | } |
| 403 | EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); |
| 404 | |
| 405 | #ifdef CONFIG_GENERIC_CPU_DEVICES |
| 406 | static DEFINE_PER_CPU(struct cpu, cpu_devices); |
| 407 | #endif |
| 408 | |
| 409 | static void __init cpu_dev_register_generic(void) |
| 410 | { |
| 411 | #ifdef CONFIG_GENERIC_CPU_DEVICES |
| 412 | int i; |
| 413 | |
| 414 | for_each_possible_cpu(i) { |
| 415 | if (register_cpu(&per_cpu(cpu_devices, i), i)) |
| 416 | panic("Failed to register CPU device"); |
| 417 | } |
| 418 | #endif |
| 419 | } |
| 420 | |
| 421 | void __init cpu_dev_init(void) |
| 422 | { |
| 423 | if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups)) |
| 424 | panic("Failed to register CPU subsystem"); |
| 425 | |
| 426 | cpu_dev_register_generic(); |
| 427 | } |